Takes a line of input and returns an array reference of tokens.
A token is an array reference containing two elements: a spacing attribute and the token text.
The spacing attribute is an integer which will be stored along with the token text in the database.
The following values are currently being used:

Takes an array reference of tokens and returns a line of output.
A token is an array reference as described in make_tokens.
The tokens will be joined together into a sentence according to the whitespace attributes associated with the tokens,
as well as any formatting provided by the tokenizer implementation.